To improve the performance and, particularly, speed of an electronic circuit system constituted by a plurality of semiconductor chips, it has become increasingly important to reduce the length of the interconnections between the semiconductor chips to a minimum.
For this purpose, a technique of minimizing the interconnections between a plurality of semiconductor chips by stacking them has been studied instead of the conventional method of mounting a plurality of semiconductor chips two-dimensionally on a multilayer board. Such a semiconductor device formed by stacking a plurality of semiconductor chips is called a multichip module.
In addition, with the use of a multichip module of this type, different types of semiconductor chips manufactured by different processes can be stacked on each other into one hybrid semiconductor device.
To manufacture a multichip module, vertically stacked semiconductor chips must be electrically connected. For the realization of such connection, the present inventors have already proposed the use of connection plugs (chip-through plugs) that extend through vertically stacked semiconductor chips to connect them (Japanese Patent Application No. 9-305784).